Vascular occlusion devices are well known in the art and can have many forms. A convenient type of occluder is one which is implanted in the vessel of a patient and is deployable via endoluminal insertion from a remote percutaneous entry point. This type of occlusion device can avoid the need for invasive open surgery, vessel ligation and so on. Some such devices can also be removable from the patient via an endoluminal retrieval procedure once no longer required.
Implantable occlusion devices of this type may either provide instantaneous occlusion of the vessel, principally by creating a physical barrier across the vessel, or may rely on the formation of a thrombus at the site of deployment of the device, in which case the device may substantially close the vessel or at least slow the flow of blood sufficiently to cause blood statis and thereby promote blood clotting.
A device which provides a total physical barrier across a vessel and thus instantaneous occlusion of the vessel can be particularly advantageous particularly when the vessel needs to be closed rapidly, for instance to perform another medical procedure or to stop blood loss from the vessel. However, these devices can be relatively difficult to deploy, typically not being suitable for delivery over a guide wire. Leaving any opening in the device for the passage of a guide wire can lead to loss of instantaneous occlusion and/or risk of leakage through the opening. For instance, a valve to close such an opening can lead to reduced compressibility for delivery purposes and is also liable to open or leak in use, thereby risking loss of occlusion function. Reliance on the creation of a thrombus to close the aperture, however small, fails to achieve instantaneous closure of the vessel, also is also at risk of recanalization.
A device which relies on causing thrombosis in the vessel can be designed for deployment over a guide wire, which can substantially facilitate the endoluminal delivery of the device into the vessel by providing a passage or lumen through the device for the guide wire. However, such devices occlude a vessel only over time, often taking hours. They can also be liable to recanalization over time.
Examples of mechanisms and devices for occluding or closing a vessel are described, for instance, in US-2008/0097509, U.S. Pat. No. 8,443,808 and U.S. Pat. No. 6,071,292.